The Blueprint

Inventory Allocation Simulator

Scenario runs freeze planning data before JuMP touches it. PostgreSQL holds audit truth while DuckDB keeps backtests off the OLTP path.

Returns & Claims Orchestration Engine

Redis events can arrive twice, late, or with stale shipment state. The architecture turns that noise into tenant-owned claims.

Compliance Document Substrate

Fourteen document families share one renderer, while invoices, credit notes, pro-forma invoices, and resolutions keep separate service paths.

Delivery Tracking Gateway

Carrier polling can return duplicates, stale events, and malformed payloads. The gateway keeps Postgres as the record and Redis as delivery.

Dispute Resolution Workbench

Six upstream exception sources feed one tenant-scoped queue. Disabled adapters, explicit correlation, and frozen audit exports keep the core independent.

SLA Penalty Settlement Engine

Penalty money needs replayable math, paired ledger rows, and disabled external clients by default. F# keeps calculation pure while Postgres owns the record.

Vendor Performance Intelligence Engine

Alert history must be byte-identical six months later, even after tenant renames and vendor merges. Frozen JSONB snapshots make audit reprints trustworthy.

Contract Lifecycle Engine

AI-extracted obligations always land in Pending, never Active. Four terminal states answer four different audit questions across 41 endpoints.

Invoice Reconciliation Engine

PO, receipt, and invoice never reconcile on first pass. Five resolution strategies with decaying confidence route matches to auto-approve or human queue.

Sensor Telemetry Engine

Rust on Tokio sustains 5,000 sensor readings per second inside 512MB. Anomaly detection runs post-flush so HTTP timeouts can't stall the ingest loop.

Subscription Lifecycle Engine

Eight subscription states with 15 valid transitions enforced in Elixir. OTP supervisors restart crashed processors; Oban handles retries on Postgres.

Clinical Scheduling Engine

Real-time slot computation under 500ms across 5 providers and 8 rooms. Double-bookings blocked by a Postgres unique constraint, not application checks.

Financial Compliance Ledger

Immutability enforced at the code layer: no UPDATE or DELETE methods on the ledger table. BIGSERIAL ordering makes tampering structurally detectable.

Webhook Ingestion Engine

Webhooks persist before anything touches them. Two-layer SSRF protection blocks creation-time lookups and re-resolves DNS on every delivery.

Workflow Automation Engine

DAGs with runtime branching via mutable skip sets instead of tangled edges. Jinja2 sandboxing isolates user expressions from the Python runtime.

Event-Driven Notification Hub

Kafka consumer sits behind a USE_KAFKA flag because Redpanda burns 150MB on a 1GB VPS. Direct HTTP ingestion and Kafka converge on one pipeline.

Multi-Agent RAG Platform

Neo4j made optional because it won't fit in a 1GB VPS. Hybrid retrieval weighs vector, keyword, and graph at 0.7, 0.2, 0.1 with graceful degradation.

Transaction Reconciliation Engine

Money as int64 cents, never floats. Two-tier Redis plus Postgres dedup with owner-verified Lua lock release across every gateway-ledger pair.

Centralized Property Intelligence Hub

PostgreSQL logical replication pulls 79 tables from four service databases into two materialized views. Refresh cadence caps scale at 50,000 properties.

Idealo Price Optimization Platform

BeautifulSoup instead of Playwright to stay under a 200MB Docker image. Celery workers self-kill at 450MB so one stuck job never drains the pool.

NBA Scenario Engine

NBA game logs only exist for games a player appeared in. A two-stage model splits DNP classification from minutes regression to escape the survivor bias.

Solar Pricing Engine

Thirteen suppliers send thirteen different CSV and XLSX formats. Per-supplier cleaners plus a two-pass matcher hit 99.5% coverage on 4,162 variants.